1. Field of the Invention
The present invention relates to a method and an apparatus for transmitting dubbing data of a digital VTR which are capable of enhancing a transmission throughput.
2. Description of the Related Art
In the case where the data which is recorded in the form of a digital format in a VTR is internationally dubbed in a remote place such as an associated country, conventionally, the dubbing is carried out through the transportation of the recording medium such as a magnetic tape. However, in this method, it takes a lot of time to carry out the dubbing. As a result, the higher speed processing has been required for the dubbing and hence the transmission through a network has been considered.
In the case where the digital data which has been reproduced by a digital VTR is transmitted to a remote place through a network, in order to realize the high speed operation, employing the double buffer system has been proposed. As shown in FIG. 8, a dubbing data transmission apparatus according to this double buffer system schematically consists of a digital VTR 51, a compression apparatus 52 for compressing the digital data which has been reproduced by the digital VTR 51, a double buffer 53 for carrying out alternately the operations of storing temporarily therein the data which has been compressed by the compression apparatus 52 and then of reading out the compressed data to output the data thus read out, and a network interface (IF) 54 for transmitting there through the data which has been read out through the double buffer 53 to a network 57. The double buffer 53 consists of a first buffer 53a and a second buffer 53b. In this connection, the data is stored in one of the buffers connected to an input side switch 55, while the data is read out from the other of the buffers connected to an output side switch 56. Both of the switches 55 and 56 are switched synchronously with each other.
However, in this dubbing data transmission apparatus according to the double buffer system, it is found out on the basis of the study made by the present inventors that there arises the problem that a null time in which no data is caused to flow through the network 57 may occur depending on the combination of both of the write speed at which the data is written to one of the buffers 53a and 53b (the encoding speed) and the read speed at which the data is read out from the other of the buffers 53a and 53b (the network speed) in some cases, so that the transmission throughput is necessarily reduced.